﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Drawing;

namespace 视频设备
{
    public partial class 生成验证码 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            //获取GB2312编码页（表） 
            /**/
            /** 
* 生成中文验证验码所要使用的方法 
* 注，生成中文验证码时要改变一下生成验证码图片的宽度 
* var imageCode = new System.Drawing.Bitmap((int)Math.Ceiling((code.Length * 22.5)), 23); //定义图片的宽度和高度 
**/
            //var gb = Encoding.GetEncoding("gb2312"); 
            /**/
            ////调用函数产生4个随机中文汉字编码 
            //object[] bytes = CreateRegionCode(4); 
            /**/
            ////根据汉字编码的字节数组解码出中文汉字 
            //var sbCode = new StringBuilder().Append(gb.GetString((byte[])Convert.ChangeType(bytes[0], typeof(byte[])))) 
            // .Append(gb.GetString((byte[])Convert.ChangeType(bytes[1], typeof(byte[])))) 
            // .Append(gb.GetString((byte[])Convert.ChangeType(bytes[2], typeof(byte[])))) 
            // .Append(gb.GetString((byte[])Convert.ChangeType(bytes[3], typeof(byte[])))); 
            //CreateCheckCodeImage(sbCode.ToString()); 
            CreateCheckCodeImage(GenerateCheckCode());
        }
        static object [] CreateRegionCode(int strLength)
        {
            var rBase=new []
            {
                "0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f" 
            };
            var random=new Random ();
            var bytes=new object [strLength ];
            /**/
            /*每循环一次产生一个含两个元素的十六进制字节数组，并将其放入bject数组中 
每个汉字有四个区位码组成 
区位码第1位和区位码第2位作为字节数组第一个元素 
区位码第3位和区位码第4位作为字节数组第二个元素 
*/ 
            for (int i=0;i<strLength ;i++)
            {
                //区位码第一位
                var r1=random .Next (11,14);
                var str_r1=rBase [r1].Trim ();
                random =new Random (r1 *unchecked ((int)DateTime .Now .Ticks )+i);//更换随机数发生器的种子避免产生重复值 
                var r2=0;
                if (r1==13)
                    r2=random .Next (0,7);
                else 
                    r2 =random .Next (0,16);
                var str_r2=rBase [r2].Trim ();
                //区位码第三位
                random =new Random (r2 *unchecked ((int)DateTime .Now .Ticks )+i);
                var r3=random .Next (10,16);
                var str_r3=rBase [r3].Trim ();
                //区位码第四位
                random =new Random (r3 *unchecked ((int)DateTime .Now .Ticks )+i);
                var r4=0;
                if (r3 == 10)
                    r4 = random.Next(1, 16);
                else if (r3 == 15)
                    r4 = random.Next(0, 15);
                else
                    r4 = random.Next(0, 16);
                var str_r4 = rBase[r4].Trim();
                var byte1 = Convert.ToByte(str_r1 + str_r2, 16);
                var byte2 = Convert.ToByte(str_r3 + str_r4, 16);
                //将两个字节变量存储在字节数组中 
                var str_r = new[] { byte1, byte2 };
                //将产生的一个汉字的字节数组放入object数组中 
                bytes.SetValue(str_r, i);
            }
            return bytes;
        }
        //#endregion 
        //生成图片#region 生成图片 
        void CreateCheckCodeImage(string code)
        {
            var imageCode = new System.Drawing.Bitmap((int)Math.Ceiling((code.Length * 12.5)), 23); //定义图片的宽度和高度 
            var g = Graphics.FromImage(imageCode); //加载图片到画布上 
            try
            {
                var random = new Random();
                g.Clear(Color.White); //清空图片背景色 
                //画图片的背景噪音线 
                for (int i = 0; i < 25; i++)
                {
                    var x1 = random.Next(imageCode.Width);
                    var x2 = random.Next(imageCode.Width);
                    var y1 = random.Next(imageCode.Height);
                    var y2 = random.Next(imageCode.Height);
                    g.DrawLine(new Pen(Color.Silver), new Point(x1, y1), new Point(x2, y2));
                }
                var font = new System.Drawing.Font("Arial", 12F, System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic);
                var brush = new System.Drawing.Drawing2D.LinearGradientBrush(
                new Rectangle(0, 0, imageCode.Width, imageCode.Height),
                Color.Blue, Color.DarkRed, 1.2F, true);
                g.DrawString(code, font, brush, 2, 2);
                //画图片的前景噪音点 
                for (int i = 0; i < 100; i++)
                {
                    var x = random.Next(imageCode.Width);
                    var y = random.Next(imageCode.Height);
                    imageCode.SetPixel(x, y, Color.FromArgb(random.Next()));
                }
                //画图片的边框线 
                g.DrawRectangle(new Pen(Color.Silver), 0, 0, imageCode.Width - 1, imageCode.Height - 1);
                var ms = new System.IO.MemoryStream();
                imageCode.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
                Response.ClearContent();
                Response.ContentType = "image/Jpeg";
                Response.BinaryWrite(ms.ToArray());
            }
            finally
            {
                g.Dispose();
                imageCode.Dispose();
            }
        }

        //#endregion 
        //生成数据验证码#region 生成数据验证码 
        public  string GenerateCheckCode()
        {
            int number;
            char code;
            string checkCode = String.Empty;
            var random = new Random();
            for (int i = 0; i < 5; i++)
            {
                number = random.Next();
                if (number % 2 == 0)
                    code = (char)('0' + (char)(number % 10));
                else
                    code = (char)('A' + (char)(number % 26));
                checkCode += code.ToString();
            }
            return checkCode;
        }
        

    }
}